Both Labour and the Conservatives are braced for further walkouts as the creation of a new independent grouping of MPs continues to rip through the political landscape.
As members of The Independent Group (TIG) said they expected to see more MPs join them, it emerged that former prime minister David Cameron had made a last-ditch bid to try to stop a trio of Tories quitting.
High-profile ex-minister Anna Soubry said Mr Cameron had reached out to the MPs as they prepared to turn their backs on the Tories for TIG.
Ms Soubry told The Times Red Box podcast that Mr Cameron sent them a text saying: “Is it too late to persuade you to stay?”
As attacks on Theresa May from ex-Tory MPs intensified, Ms Soubry accused the Prime Minister of having a personal “problem” with immigration.
Ms Soubry told BBC2’s Newsnight: “The only reason why she will not agree to the single market is because of free movement of people.
“And I think what’s really worried me about Theresa, and she has history in the Home Office that supports this, because I’m an old barrister, I look at the evidence, and I think she’s got a problem with immigration.
“I really, honestly do.”
Asked if she meant it was a personal rather than policy issue for the PM, Ms Soubry said: “Oh yeah, I think she has a thing about immigration and I don’t know where the hell that’s come from.
“Because in a modern Conservative Party, when you again look at the evidence, you know, if we don’t have all these people that come and do all this work in our country, who on earth is going to do it?”
Fellow TIG MP Heidi Allen said that around 100 of her former colleagues on the Tory benches shared her frustrations at the direction of the Conservative Party.
Ms Allen told ITV’s Peston: “I’d say a third of the party.”
Tory former attorney general Dominic Grieve said he would leave the party if the Government backed a no-deal Brexit.
Mr Grieve told the BBC: “I can’t predict where I might be if the party goes completely off the rails – that’s another matter.”
He added: “The Government which I am supporting implementing a no-deal Brexit – what would I do?
“I would not be able to maintain my support of the Government.
“I would have to leave the party.”
Lord Peter Mandelson said he felt “morally compromised” staying in Labour following anti-Semitic abuse endured by people such as ex-Labour MP Luciana Berger.
The Labour peer told ITV’s Peston: “When I look at the sort of anti-Semitic abuse to which Luciana Berger has been subjected, but not alone, many others in the party, I feel ashamed, I feel actually quite morally compromised staying in a party that can spew out so much hatred towards other members of their own party.
“Now what is Jeremy Corbyn going to do about this? I mean, this risks growing from a splinter into a cavernous split in our party if he doesn’t take action to stop it.”
Lord Mandelson urged Labour MPs to remain in the party.
The defections of Ms Soubry, Ms Allen and Sarah Wollaston from the Tories took the number of TIG MPs to 11.
Chancellor Philip Hammond told BBC Breakfast he was “very disappointed” at the defections, adding: “The Conservative Party always has been and always must be a broad church with room for a wide range of views.”
He also said: “I very much hope that at some point in the not too distant future that the three of them will feel comfortable coming back in to the party fold.”
Ms Allen left saying she wanted “to be part of something better” and a letter from all three defectors to the Prime Minister claimed the party was “recklessly marching the country to the cliff edge of no deal”.
Mr Hammond rejected that suggestion and said: “There is no getting away from the fact that the Brexit issue is distracting all of us from getting on with the very important domestic agenda.
“I know that the Prime Minister is desperate to get this Brexit issue resolved so that she can get back to delivering on the commitment she made on the steps of Downing Street in July 2016.”